Preoperative drinking does not affect gastric contents

Gastric POCUS, an emergent tool in the assessment of perioperative fasting: Narrative review

Pulmonary aspiration during anaesthesia induction is a serious adverse event that can lead to catastrophic consequences for the patient, including death. Preoperative fasting has so been assessed on the basis of the clinical history and fasting schedules recommended by clinical guidelines. This assessment is not objective, since the presence or absence of gastric contents cannot be guaranteed. Gastric point of care ultrasound (POCUS) is an objective, simple, and rapid method for assessing fasting prior to anaesthesia induction that stratifies risk and aids in decision-making. The aim of this review is to summarize the existing literature on gastric POCUS in the assessment of preoperative fasting. For this purpose, the Pubmed and Embase were searched for relevant studies published between 2014 and 2024.

Preoperative Oral Carbohydrate for Lower Extremity Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

The purpose of this study was to evaluate the effects of preoperative oral carbohydrate (CHO) loading on postoperative insulin resistance, hospital stay, and pain in patients undergoing elective arthroplasty.

METHODS

Clinical randomized controlled trials on the effects of preoperative oral CHO loading in patients undergoing elective hip and knee arthroplasty were searched on PubMed, Web of Science, Cochrane Library, Embase, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure (CNKI) from inception to February 2024. The Cochrane Risk of Bias Assessment Tool was used to evaluate the quality of the enrolled randomized controlled trials.

RESULTS

There were 16 papers included. Meta-analysis unveiled that compared with the control group, the test group had notably reduced postoperative anxiety scores [standardized mean difference = -0.06, 95% CI (confidence interval) (-0.42 to 0.30)] and complication rates [OR (odds ratio) = 0.64, 95% CI (0.41 to 0.99)] and enhanced postoperative active GLP-1 levels after preoperative oral CHO loading [standardized mean difference = 0.46, 95% CI (0.06 to 0.86)]. There was no marked difference in postoperative blood glucose levels, hospitalization time, insulin levels, and pain score.

CONCLUSIONS

Available evidence suggests that preoperative oral CHO loading in patients undergoing arthroplasty may reduce related complications, improve postoperative active GLP-1 levels, and alleviate postoperative anxiety.

Assessing the Likelihood of Procedural Intubation During Percutaneous Coronary Intervention

BACKGROUND

Preprocedural fasting is widely used before percutaneous coronary intervention (PCI). However, the incidence of procedural intubation during PCI is unknown. This study aims to identify the incidence and predictors for procedural intubation during PCI.

METHODS AND RESULTS

A retrospective cohort study was performed on patients undergoing PCI between 2014 and 2021 within the Victorian Cardiac Outcomes Registry. Patients were classified into urgent, semiurgent, or elective PCI on the basis of recorded PCI indication. Those undergoing semiurgent or elective PCI were presumed to be fasted preprocedurally. The incidence of procedural intubation was reported for each PCI group. Inverse probability treatment weighting was used to determine the association between 30-day death and procedural intubation. Logistic regression was performed to determine clinical, procedural, and lesion characteristics associated with procedural intubation among fasted patients. Among 83 929 patients, the incidence of procedural intubation was 0.5%. Patients undergoing urgent PCI (odds ratio [OR], 19.68 [95% CI, 13.91-27.86]; P<0.01) had the highest risk of procedural intubation. Procedural intubation was associated with increased 30-day death (OR, 4.79 [95% CI, 3.29-6.96]; P<0.01). Among fasted patients, estimated glomerular filtration rate (OR, 0.99 [95% CI, 0.98-0.99]; P<0.01), cardiogenic shock (OR, 96.24 [95% CI, 56.01-165.35]; P<0.01), out-of-hospital cardiac arrest (OR, 3.42 [95% CI, 1.30-8.97]; P=0.01), femoral access (OR, 2.09 [95% CI, 1.38-3.19]; P<0.01), left main disease (OR, 5.77 [95% CI, 3.16-10.54]; P<0.01), type C lesions (OR, 3.86 [95% CI, 1.19-12.56]; P=0.03), and rotational atherectomy (OR, 2.20 [95% CI, 1.03-4.69]; P=0.04) were associated with procedural intubation.

CONCLUSIONS

Despite an association with a worse 30-day mortality rate, the incidence of procedural intubation during PCI was low. Universal preprocedural fasting may be unnecessary and could be targeted at higher-risk groups.

A Randomized Trial of Cardiac Catheterization With Fasting Versus Liberal Oral Intake: The CALORI Trial

Background

Routine preprocedural fasting before cardiac catheterization remains common practice, despite a lack of robust evidence to support this practice. We investigated the impact of a liberal nonfasting strategy vs a standardized nil per os (NPO) regimen prior to cardiac catheterization.

Methods

Adult inpatients undergoing elective or urgent cardiac catheterization were randomized (1:1 ratio) to either NPO past midnight or ad libitum intake of liquids and solids (without dietary constraints) until immediately prior to the procedure. Only patients at high risk of aspiration or undergoing complex interventions were excluded. The primary end point was preprocedural patient-reported well-being scores (scaled 0-5, with 0 signifying absence of ailment and 5 the most extreme form), for variables including hunger, fatigue, anxiety, and nausea. A composite score summed the individual scores for hunger and fatigue. Other end points were periprocedural adverse events including emesis, aspiration, or intubation, in addition to postprocedural satisfaction.

Results

A total of 198 patients (65% male and 42% Black) were included in the final analysis. There were no differences in baseline characteristics between groups. Time from most recent oral intake (liquid or solid) to the start of the procedure averaged 148 minutes for the nonfasting group and 970 minutes for the NPO strategy (P < .001). The composite preprocedural well-being score was significantly better in the nonfasting arm (2.4 ± 2.4 nonfasting vs 6.0 ± 2.5 NPO; P < .001), as were the individual components of hunger (0.9 ± 1.5 vs 3.7 ± 1.5; P < .001), fatigue (1.5 ± 1.6 vs 2.3 ± 1.8; P < .001), and nausea (0.1 ± 0.5 vs 0.5 ±1.2; P = .006). There were no significant differences in adverse events between groups. Overall postprocedural satisfaction scores were significantly better in the nonfasting vs NPO group (0.3 ± 0.7 vs 1.0 ± 1.3, respectively; P < .001).

Conclusions

In this single-center randomized trial, a liberal nonfasting strategy prior to cardiac catheterization significantly improved patient well-being and satisfaction without compromising safety. Given the findings of this and other studies, routine fasting prior to cardiac catheterization should be reconsidered.

Comparison of ultrasonographic measurement of gastric antral volume and pH with or without pharmacological acid aspiration prophylaxis in low-risk surgical patients - A randomized clinical trial

Background and Aims

The role of preoperative pharmacological prophylaxis in preventing aspiration pneumonitis under general anesthesia (GA) in patients at low risk of aspiration pneumonitis is still under debate. We addressed the need for routine pharmacological aspiration prophylaxis in at-risk population by assessing the change in gastric volume using ultrasound with and without pharmacological acid aspiration prophylaxis.

Material and Methods

A single-center, randomized double-blinded trial, with 200 adult patients scheduled for elective surgical procedures under GA, were randomized into a prophylaxis group, in which the patients received oral famotidine and metoclopramide, and a no prophylaxis group, in which the patients did not receive any prophylaxis. Gastric volume derived from preinduction measurement of gastric antral volume by ultrasound, postinduction gastric pH, and incidences of aspiration pneumonitis were compared. Bland-Altman plot was used to determine the level of agreement between measured gastric volume and ultrasonography based on calculated gastric volume.

Results

The gastric antral cross-sectional area (CSA) and volume in the no prophylaxis group (3.12 cm2 and 20.11 ml, respectively) were comparable to the prophylaxis group (2.56 cm2 and 19.67 ml, respectively) (P-values 0.97 and 0.63, respectively). Although there was a statistically significant decrease in gastric pH in the no prophylaxis group (P-value 0.01), it was not clinically significant to increase the risk of aspiration pneumonitis based on Roberts and Shirley criteria (P-value 0.39).

Conclusion

In an adequately fasted low-risk population, the amount of residual gastric volume was similar and below the aspiration threshold, regardless of the aspiration prophylaxis status.

RESIDUAL GASTRIC VOLUME IN MORBIDLY OBESE DIABETICS AFTER AN OVERNIGHT FASTING OR 3 HOURS OF A CARBOHYDRATE-ENRICHED SUPPLEMENT: A RANDOMIZED CROSSOVER PILOT STUDY

BACKGROUND

To reduce the risk of regurgitation during anesthesia for elective procedures, residual gastric volumes (RGV) have traditionally been minimized by overnight fasting. Prolonged preoperative fasting presents some adverse consequences and has been abandoned for most surgical procedures, except for obese and/or diabetic patients.

AIMS

The aim of this study was to assess the RGV in morbidly obese diabetic patients after traditional or abbreviated fasting.

METHODS

This study was approved by the Ethics Committee for Research with Human Beings from the Federal University of Mato Grosso, under number 179.017/2012. This is a prospective, randomized, and crossover design study in eight morbidly obese type II diabetic patients. RGV was measured endoscopically after either traditional overnight fasting of at least 8 hours, or after abbreviated fasting of 6 hours for solids and 3 hours for a drink containing water plus 25 g (12.5%) of maltodextrin. Data were expressed as mean and range and differences were compared with paired t-tests at p<0.05.

RESULTS

The study population had a mean age of 41.5 years (28-53), weight of 135 kg (113-196), body mass index of 48.2 kg/m2 (40-62.4), and type II diabetes for 4.5 years (1-10). The RGV after abbreviated fasting was 21.5 ml (5-40) vs 26.3 ml (7-65) after traditional fasting. This difference was not significant (p=0.82).

CONCLUSIONS

Gastric emptying in morbidly obese diabetic patients is similar after either traditional or abbreviated fasting with a carbohydrate drink.

Ultrasound evaluation of gastric emptying time of standardized high-calorie liquid meals in healthy adults: A double-blind cross-over randomized study

BACKGROUND AND AIMS

Commercially available high-calorie drinks containing fat and protein can be used as dietary supplements in surgical patients. According to preoperative fasting guidelines, high-calorie drinks are non-clear fluids and should not be consumed 6 h before elective procedures. The aim of this study was to evaluate the gastric emptying time of commercially available high-calorie drink formulations in healthy adults using gastric ultrasound.

METHODS

25 healthy adult volunteers were included in this double-blind, cross-over prospective study. On three study sessions, fasted volunteers ingested one of the three study products: a solution of 75 g of glucose in 200 ml of water, a fat-free liquid meal, and a nutritionally complete liquid meal with equal volume and energy content. Gastric ultrasound examinations were performed to evaluate the gastric contents qualitatively and the volume of the gastric contents was calculated from the cross-sectional area of the gastric antrum measured in right lateral position by using a validated model. Repeated gastric ultrasounds were performed at baseline and half-hourly after ingesting the products in supine and right lateral position until the criteria for an empty stomach were met.

RESULTS

The glucose solution and the standard fat-free high-calorie drink with the same caloric content had a median gastric emptying time of 150 min. The nutritionally complete liquid meal had a median gastric emptying time of 180 min. Gastric emptying was complete in all participants before 6 h had elapsed since ingesting the study products.

CONCLUSIONS

High calorie liquid meals have a gastric emptying time longer than the recommended fasting time for clear fluids, but shorter than the recommended fasting time for solids in healthy adults.

Ultrasonographic Assessment of Gastric Volume in Fasted Patients Undergoing Gastrointestinal Endoscopy Under Sedation

Purpose

In this prospective observational study, an ultrasonographic measurement of antral cross-sectional area (ACSA) was conducted to evaluate the gastric content and volume as well as to identify high-risk stomach in non-pregnant adult surgical patients adhering to preanesthetic fasting guidelines.

Patients and Methods

Fasted patients undergoing gastrointestinal endoscopy under sedation were included. Ultrasonographic measurements of ACSA were conducted in both semi-recumbent and right lateral decubitus positions before endoscopic procedures. Gastroscopy was employed to guide the measurement of suctioned gastric volume (GV). Ultrasonography was performed to assess gastric contents and identify patients with high-risk stomach. The relationship between ACSA and suctioned GV was also evaluated.

Results

ACSA was evaluated in 736 out of 782 patients. A significant positive correlation was discovered between ACSA in the right lateral decubitus position and suctioned GV, which was more reliable than in the semi-recumbent position. To analyze high-risk stomach with a GV > 100 mL, the cutoff value of ACSA in the right lateral decubitus was found to be 7.5 cm2, with the AUC, sensitivity and specificity of 0.80 (95% CI, 0.76-0.82; P<0.001), 82.4% and 67.3%, respectively. A novel mathematical model based on ACSA to estimate GV in non-pregnant fasted adults was presented.

Conclusion

Ultrasonographic measurement of ACSA can assist anesthesiologists in estimating the risk of pulmonary aspiration of gastric contents during general anesthesia and sedation.

Carbohydrate Loading and Aspiration Risk in Bariatric Patients: Safety in Preoperative Enhanced Recovery Protocols

BACKGROUND

Enhanced recovery protocols have been developed to improve perioperative outcomes; however, there is ongoing concern for aspiration with recent oral intake in patients with obesity, who may be predisposed to impaired gastrointestinal motility and greater gastric volumes. We aim to study the safety of a 300-mL preoperative carbohydrate-loading drink preceding bariatric surgery.

STUDY DESIGN

Data were collected prospectively from patients undergoing primary bariatric surgery. All bariatric patients at our institution are prescribed a proton pump inhibitor for 4 weeks before surgery and undergo a screening preoperative esophagogastroduodenoscopy (EGD) before surgery with a traditional 8-hour fast (NOCARB), followed by an intraoperative day-of-operation EGD with carbohydrate loading (CARB) 2 to 4 hours before incision. Gastric volumes and pH are measured after being endoscopically suctioned via direct visualization during both settings.

RESULTS

We identified 203 patients: 94 patients (46.3%) in the CARB group and 109 patients (53.7%) in the NOCARB group. The patients were 82.3% female with a mean age of 42.8 years and average BMI of 41.7 kg/m 2 . There was no difference in gastric volume between NOCARB and CARB (17.0 vs 16.1 mL, p = 0.59). The NOCARB group had lower pH values than the CARB group (2.8 vs 3.8, p = 0.001). Subset analysis of 23 patients who had measurements on both screening and intraoperative EGD revealed lower gastric volumes in CARB patients (13.3 vs 18.3, p < 0.0001).

CONCLUSIONS

When included in an enhanced recovery protocol, proton pump inhibitor use and preoperative carbohydrate loading 2 to 4 hours before bariatric surgery does not increase aspiration risk based on gastric volumes and pH and should be strongly considered in all eligible bariatric patients.

Clinical practice guidelines for enhanced recovery after colon and rectal surgery from the American Society of Colon and Rectal Surgeons and the Society of American Gastrointestinal and Endoscopic Surgeons

The American Society of Colon and Rectal Surgeons (ASCRS) and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) are dedicated to ensuring high-quality innovative patient care for surgical patients by advancing the science, prevention, and management of disorders and diseases of the colon, rectum, and anus as well as minimally invasive surgery. The ASCRS and SAGES society members involved in the creation of these guidelines were chosen because they have demonstrated expertise in the specialty of colon and rectal surgery and enhanced recovery. This consensus document was created to lead international efforts in defining quality care for conditions related to the colon, rectum, and anus and develop clinical practice guidelines based on the best available evidence. While not proscriptive, these guidelines provide information on which decisions can be made and do not dictate a specific form of treatment. These guidelines are intended for the use of all practitioners, healthcare workers, and patients who desire information about the management of the conditions addressed by the topics covered in these guidelines. These guidelines should not be deemed inclusive of all proper methods of care nor exclusive of methods of care reasonably directed toward obtaining the same results. The ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of all the circumstances presented by the individual patient. This clinical practice guideline represents a collaborative effort between the American Society of Colon and Rectal Surgeons (ASCRS) and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) and was approved by both societies.

Preoperative carbohydrate loading before colorectal surgery: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Preoperative carbohydrate loading has been introduced as a component of many enhanced recovery after surgery programs. Evaluation of current evidence for preoperative carbohydrate loading in colorectal surgery has never been synthesized.

METHODS

MEDLINE, Embase, and CENTRAL were searched until May 2021. Randomized controlled trials (RCTs) comparing patients undergoing colorectal surgery with and without preoperative carbohydrate loading were included. Primary outcomes were changes in blood insulin and glucose levels. A pairwise meta-analysis was performed using inverse variance random effects.

RESULTS

The search yielded 3656 citations, from which 12 RCTs were included. In total, 387 patients given preoperative carbohydrate loading (47.2% female, age: 62.0 years) and 371 patients in control groups (49.4% female, age: 61.1 years) were included. There was no statistical difference for blood glucose and insulin levels between both patient groups. Patients receiving preoperative carbohydrate loading experienced a shorter time to first flatus (SMD: - 0.48 days, 95% CI: - 0.84 to - 0.12, p = 0.008) and stool (SMD: - 0.50 days, 95% CI: - 0.86 to - 0.14, p = 0.007). Additionally, length of stay was shorter in the preoperative carbohydrate loading group (SMD: - 0.51 days, 95% CI: - 0.88 to - 0.14, p = 0.007). There was no difference in postoperative morbidity and patient well-being between both groups.

CONCLUSIONS

Preoperative carbohydrate loading does not significantly impact postoperative glycemic control in patients undergoing colorectal surgery; however, it may be associated with a shorter length of stay and faster return of bowel function. It merits consideration for inclusion within colorectal enhanced recovery after surgery protocols.

Gastric Emptying of Orange Juice With and Without Pulp: A Point-of-Care Ultrasound Study

Purpose The American Society of Anesthesiologists (ASA) preoperative fasting recommendations regarding fruit juice with pulp is unclear. In addition, it is debatable whether orange juice without pulp should be treated as a clear liquid. Our objective is to determine the gastric emptying time of orange juice with and without pulp. Methods This is an observational study of gastric emptying time using point-of-care ultrasound (POCUS). Thirty-five adult volunteers were enrolled in this study. Exclusion criteria included pregnancy, diabetes, body mass index > 40 kg/m², previous lower esophageal or upper abdominal surgery, hiatal hernia, and upper gastrointestinal bleed. The study was carried out on three separate days for each volunteer. After fasting a minimum of 8 h, the volunteers were asked to drink 240 ml of water on day 1, orange juice without pulp on day 2, and orange juice with pulp on day 3. Gastric volumes were estimated using gastric antrum cross-sectional area at fasting state, and then 30, 60, 90 120, 180, and 240 min after drinking until the gastric volume returned to baseline. Results A gastric volume of 1.5 mL/kg was defined as a baseline. All subjects' gastric volume returned to baseline 90 min after drinking water. More than 97% of the subjects who drank orange juice without pulp and 93.9% of the subjects who drank orange juice with pulp reached a gastric volume of less than 1.5 mL/kg after 2 h. All subjects' gastric volume returned to baseline 3 h after drinking orange juice with pulp. Conclusions Orange juice without pulp can be treated as a clear liquid in a majority of patients who do not have conditions that would cause delayed gastric emptying. Orange juice with pulp required 3 h to empty.

Review of paediatric gastrointestinal physiology relevant to the absorption of orally administered medicines

Despite much progress in regulations to improve paediatric drug development, there remains a significant need to develop better medications for children. For the design of oral dosage forms, a detailed understanding of the specific gastrointestinal (GI) conditions in children of different age categories and how they differ from GI conditions in adults is essential. Several review articles have been published addressing the ontogeny of GI characteristics, including luminal conditions in the GI tract of children. However, the data reported in most of these reviews are of limited quality because (1) information was cited from very old publications and sometimes low quality sources, (2) data gaps in the original data were filled with textbook knowledge, (3) data obtained on healthy and sick children were mixed, (4) average data obtained on groups of patients were mixed with data obtained on individual patients, and (5) results obtained using investigative techniques that may have altered the outcome of the respective studies were considered. Consequently, many of these reviews draw conclusions that may be incorrect. The aim of the present review was to provide a comprehensive and updated overview of the available original data on the ontogeny of GI luminal conditions relevant to oral drug absorption in the paediatric population. To this end, the PubMed and Web of Science metadatabases were searched for appropriate studies that examined age-related conditions in the oral cavity, esophagus, stomach, small intestine, and colon. Maturation was observed for several GI parameters, and corresponding data sets were identified for each paediatric age group. However, it also became clear that the ontogeny of several GI traits in the paediatric population is not yet known. The review article provides a robust and valuable data set for the development of paediatric in vitro and in silico biopharmaceutical tools to support the development of age-appropriate dosage forms. In addition, it provides important information on existing data gaps and should provide impetus for further systematic and well-designed in vivo studies on GI physiology in children of specific age groups in order to close existing knowledge gaps and to sustainably improve oral drug therapy in children.

Enhanced Recovery After Gastrointestinal Surgery (ERAS) in Pediatric Patients: a Systematic Review and Meta-analysis

AIM

To systematically review literature and to assess the status of the ERAS protocol in pediatric populations undergoing gastrointestinal surgery.

METHODS

Literature research was carried out for papers comparing ERAS and traditional protocol in children undergoing gastrointestinal surgery. Data on complications, hospital readmission, length of hospital stay, intraoperative fluid volume, post-operative opioid usage, time to defecation, regular diet, intravenous fluid stop, and costs were collected and analyzed. Analyses were performed using OR and CI 95%. A p value <0.05 was considered significant.

RESULTS

A total of 8 papers met the inclusion criteria, with 943 included patients. There was no significant difference in complication occurrence and 30-day readmission. Differently, length of stay, intraoperative fluid volume, post-operative opioid use, time to first defecation, time to regular diet, time to intravenous fluid stop, and costs were significantly lower in the ERAS groups.

CONCLUSIONS

ERAS protocol is safe and feasible for children undergoing gastrointestinal surgery. Without any significant complications and hospital readmission, it decreases length of stay, ameliorates the recovery of gastrointestinal function, and reduces the needs of perioperative infusion, post-operative opioid administration, and costs.

GASTRIC RESIDUAL VOLUME FACTORS AFTER BOWEL PREPARATION WITH MANNITOL EXPRESS

BACKGROUND

Bowel preparation with mannitol is a well-established method in Brazil. However, factors that interfere with the gastric emptying time period are yet to be known. Knowing these factors may favor the examination scheduling logistics and the individualized orientation for each patient.

OBJECTIVE

Know the factors that can contribute to the gastric emptying time after intestinal preparation with express mannitol.

METHODS

This is a prospective observational study to know factors that may contribute on the gastric emptying timing: predominant type of diet, comorbidities, medication usage, previous surgeries, number of evacuation per week, bearer of bowel obstipation, fecal type, diet type, number of evacuations after the home usage of bisacodyl before the ingestion of mannitol and number of evacuations after the ingestion of mannitol until reaching a proper bowel preparation. Before starting the colonoscopy exam, an upper digestive endoscopy exam was made to aspirate the gastric content.

RESULTS

Sample was composed of 103 patients, 55 (53.4%) women, medium age 61 (±12.1) years, medium weight 75.3 (±14.1) kg, medium height 1.7 (±10) m and medium BMI of 26.6 (±3.9) kg/m2. Average gastric residual volume was 120.9 (0-900) mL. Gastric residual volume (GRV) below 100 mL (GRV ≤100 mL) occurred in 45 (43.6%) patients, 24 (53.3%) women, medium age of 61.0 years and medium BMI of 26.7 kg/m2. Gastric residual volume above 100 mL (GRV >100 mL) occurred on 58 (56.3%) patients, 29 (50%) women, medium age of 61.0 years and medium BMI of 26.2 kg/m2. Comparing both groups, average fasting time period after the ingestion of mannitol was significantly higher on the group with GRV ≤100 mL than group with GRV >100 mL, 123.1 (60-246) vs 95.3 (55-195) minutes, respectively. There was also statistical significance concerning the usage of ezetimibe 6 (13.7%) in the group with GRV ≤100 mL and statistical significance in the group with GRV >100 mL concerning the usage of paroxetine 3 (6.7%) and tadalafil 3 (6.7%) and surgical history of prostatectomy 3 (6.7%) and bridle withdrawal 3 (6.7%).

CONCLUSION

We may conclude in this study that the usage of ezetimibe and fasting above 2 hours after the ingestion of mannitol decrease significantly the incidence of a GRV >100 mL. The usage of paroxetine, tadalafil and surgical history of prostatectomy or bridle withdrawal may contribute to increase de incidence of a GRV >100 mL.

Gastric Residual Volume Assessment by Gastric Ultrasound in Fasting Obese Patients: A Comparative Study

Background

Gastric ultrasound is an emerging tool for preoperative evaluation of gastric content and volume.

Objectives

To assess gastric residual volume in normal-weight and obese patients scheduled for elective surgery.

Methods

This prospective observational study was conducted on 100 patients assigned to two groups of 50 patients each. The obese group included patients with body mass index (BMI) of 30 - 40 and American Society of Anesthesiologists (ASA) grade II and those with BMI > 40 and ASA III without other comorbidities; the normal-weight group included patients with normal BMI and ASA I. Gastric volume was predicted in each group using sonographic measurement of antral cross-sectional area (CSA) in semi-sitting and right lateral positions (RLP); the two groups were compared to assess the risk of aspiration for each group preoperatively.

Results

Despite intergroup differences in antral CSA, the sonographically predicted gastric volume was < 1.5 mL/kg in both groups in both positions. Both groups were at a low risk for aspiration, and 98% of the patients showed grade 0 or 1 in antrum assessments, corresponding to an empty antrum and minimal fluid only in the RLP, respectively. Only 2% of the patients in both groups showed a distended antrum in both positions.

Conclusions

Despite the differences in CSA between obese and normal-weight participants in both positions (obese > normal-weight), both groups showed a low predicted gastric residual volume < 1.5 mL/kg and were at low risk for aspiration, provided that fasting was initiated at least 8 hours before elective surgery.

Efficacy of single- versus split-dose polyethylene glycol electrolyte solution for morning colonoscopy: A randomized controlled study

BACKGROUND

Split-dose (SPD) regimen has been proved more effective than a single-dose (SID) regimen for various drug preparations; however, limited data have focused on morning colonoscopy. We implemented this study to compare the bowel cleanliness and tolerability of a same-day SID versus SPD 2 L polyethylene glycol electrolyte solution (PEG) for morning colonoscopy.

METHODS

Patients undergoing morning colonoscopy were randomized into two groups, SID or SPD. In the SID group, patients had to complete 2 L PEG between 4 and 6 am on the day of colonoscopy. In the SPD group, patients had to complete 1 L PEG between 8 and 9 pm on the day before followed by another 1 L PEG between 5 and 6 am on the day of colonoscopy. Colonoscopy was performed between 8 and 12 am under anesthesia. Investigators and endoscopists were blinded to the allocation. The primary end point was the effectiveness of bowel cleansing according to the Boston Bowel Preparation Scale (BBPS). The secondary outcomes were polyp detection rate, compliance, tolerability, and patient satisfaction.

RESULTS

Overall, there were 147 and 148 patients in the SID and SPD group, respectively. The SPD group had a better quality of bowel preparation than the SID group with a total BBPS score of 7.25 ± 1.53 versus 6.71 ± 1.65 (P = 0.005). No difference in the polyp detection rate was noted, although more polyps were detected in the SPD group. More patients felt acceptable with the bowel preparation regimen in the SPD group compared to the SID group (76% vs. 65%, P = 0.03). The adverse events were more commonly observed in the SID group, presented as nausea and vomiting.

CONCLUSION

For morning colonoscopy, split-dose 2 L PEG is superior to single-dose 2 L PEG by improved bowel preparation, better tolerability, and patient satisfaction.

Gastric point-of-care ultrasound (PoCUS) during pregnancy and the postpartum period: a systematic review

Personalised risk assessment of the likelihood of pulmonary aspiration is recommended for pregnant women undergoing general anaesthesia and gastric point-of-care ultrasound (PoCUS) may help to achieve this. Traditionally, risk assessment is based upon adherence to fasting times, but gastric emptying may vary during pregnancy and surgery often needs to be expedited. We systematically reviewed the evidence for gastric PoCUS up to August 2018 in pregnant and postpartum women to determine whether it can identify and quantify stomach contents, provide aspiration risk assessment via qualitative or quantitative means, and determine how gastric emptying is affected by pregnancy. Twenty-two articles comprising 1050 participants were included and studies were classified by qualitative or quantitative findings. The evidence suggests that gastric PoCUS is a reliable and feasible method of imaging the stomach in pregnancy in clinical practice. Qualitative assessment via the Perlas grading system can provide rapid assessment of gastric volume states. If fluid is visible, identification of patients at high risk of pulmonary aspiration requires measurement of antral cross-sectional area. Cut-off values of 608 mm² and 960 mm² are recommended in the semi-recumbent and right lateral semi-recumbent positions, respectively. Validated methods to quantify stomach volumes are available, however their usefulness is currently restricted to research. Gastric PoCUS also provides evidence that gastric emptying of ingested food is delayed by term pregnancy, labour and during the early postpartum period. However, the passage of fluids through the stomach appears unaffected throughout the peripartum period.

Exploring the Role of Cereal Dietary Fiber in Digestion

Increasing the dietary fiber of staple foods such as bread is an attractive way to promote healthy eating in a large part of the population, where dietary fiber consumption is reportedly below the recommended values. However, many consumers prefer white breads, which are typically low in dietary fiber. In this work, white bread was made from two wheat cultivars with differing fiber contents. The resulting breads showed similar quality parameters (volume, specific volume, firmness, inner structure characteristics) with any differences maintained below 7%. Bread digestibility was evaluated using a novel dynamic in vitro digestion model. Reduced digestion rates of 30% were estimated for the high-fiber white bread compared to that in the control. Overall, this work demonstrates the potential to produce healthy, high-fiber white breads that are acceptable to consumers, with a reduced rate of starch digestion, by exploiting a genetic variation in the dietary fiber content of wheat cultivars.

Effect of pre-operative oral carbohydrate loading on recovery after day-case cholecystectomy: A randomised controlled trial

BACKGROUND

Pre-operative carbohydrate loading has been shown to reduce pre-operative discomfort and postoperative nausea and vomiting in general surgical patients. Few studies have considered day-case surgery.

OBJECTIVE

The aim of this prospective randomised study was to determine whether pre-operative carbohydrate loading enhanced recovery after day-case cholecystectomy.

DESIGN

A randomised controlled trial.

SETTING

Secondary care in a district general and a university hospital in Finland between 2013 and 2016.

PATIENTS

A total of 113 patients American Society of Anesthesiologists physical status I or II aged 18 to 70 undergoing day-case cholecystectomy were included in the study. Exclusion criteria were bleeding or coagulation disorders, BMI more than 40 kg m, dementia, insulin-treated diabetes, migraine, Meniere's disease or a history of alcohol or drug abuse.

INTERVENTION

The carbohydrate-rich drink group received oral carbohydrate (200 ml) 2 to 3 h before surgery, and the control (fasting) group fasted from midnight according to standard protocol.

MAIN OUTCOME MEASURES

Visual analogue scales (VAS) were used to score six forms of discomfort: the need for analgesia and antiemetics, the time to drinking, eating and first mobilisation after surgery and the time to discharge. Any hospital re-admission was also recorded.

RESULTS

The highest VAS scores were seen for mouth dryness and tiredness 2 h after surgery in the fasting group. There were no significant differences in any VAS scores between the study groups. No differences in time to mobilisation, need for pain or antiemetic medication or time to discharge were seen between the groups.

CONCLUSION

Compared with overnight fasting, pre-operative carbohydrate loading did not significantly enhance peri-operative well being or recovery in patients undergoing day-case cholecystectomy.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT03757208.

Intravenous Fluid to Prevent Hypotension in Patients Undergoing Elective Colonoscopy

Colonoscopy may be associated with hypotension during sedation leading to postoperative morbidity. However, no treatment is proven to ameliorate intraoperative hypotension for this procedure. We therefore conducted a randomized trial to determine the effect of intravenous fluid infusion on the incidence of hypotension during sedation for colonoscopy. With institutional approval, 160 patients presenting for elective colonoscopy were randomized to 1.5 ml/kg or 15 ml/kg Hartmann's solution before colonoscopy. All observers were blind to group allocation. The incidence of hypotension during sedation (29% vs 25%; P=0.59) and postoperative morbidity (nausea, vomiting, headache, drowsiness and dizziness) (41% vs 39%; P=0.75) did not differ between the two groups. Hypotensive patients were older, had a higher baseline systolic blood pressure, and were thirstier after fluid infusion than normotensive patients. This study does not support the use of 15 ml/kg Hartmann's solution to reduce the incidence of hypotension or postoperative morbidity in patients undergoing elective colonoscopy.

Preoperative Gastric Residual Volumes in Fasted Patients Measured by Bedside Ultrasound: A Prospective Observational Study

The purpose of this prospective observational study was to measure gastric volumes in fasted patients using bedside gastric ultrasound. Patients presenting for non-emergency surgery underwent a gastric antrum assessment, using the two-diameter and free-trace methods to determine antral cross-sectional area. Gastric residual volume (GRV) was calculated using a validated formula. Univariate and multivariable analyses were performed to examine any potential relationships between ‘at risk’ GRVs (>100 ml) and patient factors. Two hundred and twenty-two successful scans were performed; of these 110 patients (49.5%) had an empty stomach, nine patients (4.1%) had a GRV >100 ml, and a further six patients (2.7%) had a GRV >1.5 ml/kg. There was no significant relationship between ‘at risk’ GRV and obesity, diabetes mellitus, gastro-oesophageal reflux disease or opioid use, although our study had insufficient power to exclude an influence of one or more of these factors. Our results indicate that despite compliance with fasting guidelines, a small percentage of patients still have GRVs that pose a pulmonary aspiration risk. Anaesthetists should consider this background incidence when choosing anaesthesia techniques for their patients. While future observational studies are required to determine the role of preoperative bedside gastric ultrasound, it is possible that this technique may assist anaesthetists in identifying patients with ‘at risk’ GRVs.

Term pregnant patients have similar gastric volume to non-pregnant females: a single-centre cohort study

BACKGROUND

The physiological changes of pregnancy can increase the risk of peri-partum pulmonary aspiration. There is limited objective information regarding gastric volumes in pregnant patients. The aim of this cohort study was to characterise prospectively the range of gastric-fluid volume in term non-labouring pregnant patients compared with a historical cohort of non-pregnant females.

METHODS

Fasted non-labouring term pregnant patients scheduled for elective Caesarean delivery underwent a standardised gastric ultrasound examination. Gastric content was evaluated qualitatively (type of content), semi-quantitatively (Perlas grades), and quantitatively (volume). The antral cross-sectional area and volume were compared with those of a retrospective cohort of non-pregnant females from the same institution. Descriptive statistics were used to describe the central tendency through mean and median values. Dispersion was evaluated with standard deviation and inter-quartile range, and the higher end of the distribution as 95th percentile.

RESULTS

Non-labouring pregnant (59) and non-pregnant (81) subjects were studied. The range of estimated total gastric-fluid volume (P=0.96) and volume per body weight (P=0.78) was not significantly different between cohorts. An estimated volume of 115 ml (102-143) vs 136 ml (106-149) and volume per body weight of 1.4 ml kg^-1 (1.2-2.8) vs 2.0 ml kg^-1 (1.5-2.7) corresponded to the 95th percentile (95% confidence interval) values in the pregnant and non-pregnant cohort, respectively.

CONCLUSIONS

Baseline gastric volume of non-labouring pregnant patients at term is not significantly different from that of non-pregnant females. This information will be helpful to interpreting findings of gastric point-of-care ultrasound in obstetric patients.

Preoperative anesthesia evaluation

The preoperative evaluation is the first step in ensuring the safe conduct of anesthetic care in pediatric patients of all ages. Over time, this process has changed significantly from a time when patients were admitted to the hospital the night before surgery to a time when the majority of patients, including those scheduled for major surgical procedures, arrive the day of surgery. For most patients, the preoperative examiantion can be conducted over the phone by a trained nurse or on-line via a survey thereby eliminating the need for a separate visit merely for the preoperative evaluation. Regardless of where or how it occurs, the goals of the preoperative evaluation are to gain information regarding the patient's current status, comorbid conditions, and the intended procedure. This process allows the identification of patients who require additional preoperative testing or those patients who need to be seen by an anesthesiolgoist prior to the day of surgery. During the preopeative evalaution, decisions are made regarding further laboratory or investigative work-up that are required. The preoperative meeting provides an arena to develop the initial parent-physcian rapport, outline anesthetic risks, and discuss the intended anesthetic plan including options for postoperative analgesia. The process facilitates the care of patients during the perioperative period while limiting surgical cancellations resulting from patient-related issues. The following chapter reviews the essential components of the preoperative evaluation including the appropraite use of preoperative laboratory testing and other investigative procedures including radiologic imaging. Key components of the physical examinatino including the airway examination are reviewed.

Enhanced recovery pathways in thoracic surgery from Italian VATS Group: preoperative optimisation

Preoperative patient optimisation is a key point of enhanced recovery after thoracic surgery pathways. This could be particularly advantageous when considering video-assisted thoracic surgery (VATS) lobectomy, because reduced trauma related to minimally invasive techniques is one of the main factors favouring improved postoperative outcome. Main specific interventions for clinical optimisation before major lung resection include assessment and treatment of comorbidities, minimizing preoperative hospitalization, optimisation of pharmacological prophylaxis (antibiotic and thromboembolic) and minimizing preoperative fasting. Literature data and clinical evidences in this setting are reported and discussed.

Enhanced recovery after surgery (ERAS) and fast-track in video-assisted thoracic surgery (VATS) lobectomy: preoperative optimisation and care-plans

Main specific interventions for preoperative clinical optimisation of patients undergoing lung cancer surgery include assessment and treatment of comorbidities, minimizing preoperative hospitalization, minimizing preoperative fasting, and optimisation of antibiotic and thrombo-embolic prophylaxis. Preoperative patient optimisation is considered a crucial part of enhanced recovery after thoracic surgery pathways. Potentially, advantages of this fast-track management could be even higher when considering video-assisted thoracic surgery (VATS) major lung resection, because reduced trauma related to minimally invasive techniques is one of the main factors improving postoperative outcome. Literature data and clinical evidences in this setting are reported and discussed.

Interactions between acid and proteins underin vitrogastric condition – a theoretical and experimental quantification

The ionizable amino acid side groups in protein determine its buffer capacity. Buffer capacity influences the acid diffusion in protein-based structures.

Bladder Cancer Recovery Pathways: A Systematic Review

BACKGROUND

Enhanced recovery pathways, also known as fast-track protocols, have been adopted since the early 2000s by various surgical specialties with the goal of improving patient outcomes and reducing the cost burden of major surgery on the health care system.

OBJECTIVE

To review the scientific literature on the origin of enhanced recovery pathways, track the contemporary utilization of such practices for patients undergoing radical cystectomy, and analyze the available data regarding their effect on morbidity, mortality, and treatment cost.

METHODS

A literature search of multiple electronic databases was undertaken. Manuscripts including patients undergoing radical cystectomy were chosen based on predefined criteria with an emphasis on randomized controlled trials and cohort studies. Strength of evidence for each study that met inclusion criteria was assessed based on the risk of bias, consistency, directness, and precision.

RESULTS

Database searches resulted in 1,236 potentially relevant articles. A total of 485 articles were selected for full-text dual review and 106 studies in 52 publications met the inclusion criteria.

CONCLUSION

The utilization of enhanced recovery pathways with the goal of improving overall patient morbidity and mortality is well supported in the literature, however standardization of implementation and adherence across institutions is lacking, and their direct efficacy on reducing preventable treatment related expenditures is unconfirmed.

Qualitative and quantitative ultrasound assessment of gastric content

Objective:

Pulmonary aspiration of the gastric contents is one of the most feared complications in anesthesia. Its prevention depends on preoperative fasting as well as identification of risky patients. A reliable diagnostic tool to assess gastric volume is currently lacking. The aim of this study performed on volunteers was to evaluate the feasibility of ultrasonography to identify qualitative and quantitative gastric content.

Method:

A standardized gastric scanning protocol was applied on 67 healthy volunteers to assess the gastric antrum in four different situations: fasting, after ingesting clear fluid, milk and a solid meal. A qualitative and quantitative assessment of the gastric content in the antrum was performed by a blinded sonographer. The antrum was considered either as empty, or containing clear or thick fluid, or solids. Total gastric volume was predicted based on a cross-sectional area of the antrum. A p-value less than 0.05 was considered statistically significant.

Results:

For each type of gastric content, the sonographic characteristics of the antrum and its content were described and illustrated. Sonographic qualitative assessment allowed to distinguish between an empty stomach and one with different kinds of meal. The predicted gastric volume was significantly larger after the consumption of any food source compared to fasting.

Conclusion:

Bedside sonography can determine the nature of gastric content. It is also possible to estimate the difference between an empty gastric antrum and one that has some food in it. Such information may be useful to estimate the risk of aspiration, particularly in situations when prandial status is unknown or uncertain.

Variability in Perioperative Fasting Practices Negatively Impacts Nutritional Support of Critically Ill Intubated Patients

The aim of the study was to quantify nutritional losses related to pre- and postoperative fasts in critically ill intubated patients and to explore whether shorter fasts are safe and appropriate in this population. A retrospective review of mechanically ventilated adults undergoing surgery more than 24 hours after admission to a Level I trauma center over 15 months was done, which yielded 132 procedures and 81 unique patients. Ninety per cent of preoperative periods and 43 per cent of postoperative periods were affected by nonmedical barriers to feeding. Eighty-two per cent of gastrically fed nonemergent cases were fasted for longer than the 6-hour American Society of Anesthesiologists guideline, whereas 91 per cent of emergent cases had shorter fasts. There were no anesthetic complications, placing an upper limit of 6 per cent on the rate of aspiration for fasts shorter than six hours (95% confidence). Forty-three per cent of cases did not resume tube feeds within 90 minutes postoperatively, and only 37 per cent had a documented justification for delay. Intubated patients were frequently fasted preoperatively for longer than recommended and postoperatively for longer than medically indicated. No complications were observed with shorter-than-guideline fasts. This strengthens the evidence that “standard” preoperative fasting is unnecessary and deleterious in many critically ill intubated patients. New protocols and national guidelines are needed to ensure adequate nutrition.

Residual Gastric Volume After Bowel Preparation With Polyethylene Glycol for Elective Colonoscopy: A Prospective Observational Study

GOAL

To examine the residual gastric volume (RGV) in colonoscopy after bowel preparations with 3-L polyethylene glycol (PEG).

BACKGROUND

Obstacles to high-volume bowel preparation by anesthesia providers resulting from concerns over aspiration risk are common during colonoscopy.

STUDY

Prospective measurements of RGV were performed in patients undergoing esophagogastroduodenoscopy (EGD) and morning colonoscopy with split-dose PEG preparation, patients undergoing EGD and afternoon colonoscopy with same-day PEG preparation, and patients undergoing EGD alone under moderate conscious sedation. Colonoscopy patients were allowed to ingest clear liquids until 2 hours before the procedure. Patients undergoing EGD alone were instructed to eat/drink nothing after midnight.

RESULTS

There were 860 evaluated patients, including 330 in the split-dose preparation group, 100 in the same-day preparation group, and 430 in the EGD-only group. Baseline demographics and disease/medication factors were similar. The mean RGV in patients receiving the same-day preparation (35.4 mL or 0.56 mL/kg) was significantly higher than that in patients receiving the split-dose preparation (28.5 mL or 0.45 mL/kg) and in patients undergoing EGD alone (22.8 mL or 0.36 mL/kg) (P=0.023 and P<0.0001, respectively). Within the bowel-preparation groups, patients with fasting times of 2 to 3 hours had similar RGV compared with patients who had fasting times >3 hours. The shape of the distribution and the range of RGV among the 3 study groups were similar. No aspiration occurred in any group.

CONCLUSIONS

PEG bowel preparations increase RGV mildly, but seem to have no clinical significance. These results support the current fasting guidelines for colonoscopy.

Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration: Application to Healthy Patients Undergoing Elective Procedures

Supplemental Digital Content is available in the text.

Split-dose bowel preparation with polyethylene glycol for colonoscopy performed under propofol sedation. Is there an optimal timing?

OBJECTIVE

Aspiration risk, especially with propofol sedation, remains a concern after split-dose bowel preparation of up to 1 L polyethylene glycol for the procedure. We aimed to identify the ideal timing of bowel preparation to achieve optimal colon cleansing with no increased risk of aspiration.

METHODS

A total of 892 consecutive patients undergoing simultaneous esophagogastroduodenoscopy (EGD) and colonoscopy were prospectively recruited. Residual gastric volume (RGV) and pH of gastric contents were measured at EGD, and patients' characteristics, runway time (duration between completion of the final liter of bowel preparation and colonoscopy commencement), and cleansing quality were recorded.

RESULTS

A shorter runway time resulted in better colon cleansing (r = -0.124, P < 0.001). No correlation between runway time and RGV or pH was found (r = -0.017, P = 0.62 and r = -0.030, P = 0.47, respectively). RGV and pH did not differ significantly with runway time of 4 or 5 h. RGV with runway time ≤3 h was 35.9 ± 11.8 mL and 17.4 ± 0.6 mL after runway time >3 h (P < 0.001). No aspiration pneumonia occurred. The only factors independently related to higher RGV were younger age and male sex.

CONCLUSIONS

The consumption of bowel preparation agent within 3-4 h before propofol sedation resulted in a similar RGV and pH as those achieved by more prolonged fasting, with no increased risk of aspiration even in patients perceived to be at high risk.

Reducing pre-operative fasting while preserving operating room scheduling flexibility: feasibility and impact on patient discomfort

BACKGROUND

The need to preserve operating room (OR) scheduling flexibility can challenge adherence to the 2-h pre-operative fasting period recommendation before elective surgery. Our primary objective was to assess the feasibility of a pre-operative carbohydrate (CHO) drink delivery strategy preserving OR scheduling flexibility.

METHODS

During the 1st study phase, patients admitted for elective surgery fasted overnight (Control group); during the 2nd phase, patients fasted overnight and received a pre-operative CHO drink (CHO group). CHO delivery time was set to allow any patient to be ready for surgery 30 min ahead of the scheduled time and any patient with an operation scheduled in the afternoon to be ready at 13:00 hours; patients admitted the morning of an early morning operation would not be allowed to take a CHO drink.

RESULTS

We included 194 patients in the Control group and 199 in the CHO group. In the CHO group, the morning CHO dose was delivered to 66.3% of the patients (95% CI 59.3-72.9%), with a median pre-operative fasting time period of 4 h 57 min. After excluding patients admitted the morning of an operation scheduled before 10:00 hours, the delivery rate was 77.2% (70.2-83.3%). Patients in the CHO group experienced significantly less pre-operative thirst (median 2 vs. 5 on a 0-10 scale, P < 0.0001) and hunger (0 vs. 2, P < 0.0001) than those in the Control group.

CONCLUSION

Although preservation of OR scheduling flexibility resulted in a longer fasting time than recommended, CHO drink can be made available to a large proportion of patients with significantly reduced perioperative discomfort.

[Use of ultrasound for gastric volume evaluation after ingestion of different volumes of isotonic solution]

BACKGROUND AND OBJECTIVES

The current preoperative fasting guidelines allow fluid intake up to 2hours before surgery. The aim of this study was to evaluate the gastric volume of volunteers after an overnight fast and compare it with the gastric volume 2hours after ingestion of 200 and 500mL of isotonic solution, by means of ultrasound assessment.

METHOD

Eighty volunteers underwent gastric ultrasound at three times: after 8hours of fasting; 2hours after ingestion of 200mL isotonic saline, followed by the first scan; and on another day, 2hours after ingestion of 500mL of the same solution after an overnight fast. The evaluation was quantitative (antrum area and gastric volume, and the ratio of participants' gastric volume/weight) and qualitative (absence or presence of gastric contents on right lateral decubitus and supine positions. A p-value<0.05 was considered significant).

RESULTS

There was no difference in quantitative variables at measurement times (p>0.05). Five volunteers (6.25%) had a volume/weight over 1.5mL.kg^-1 at fasting and 2hours after ingestion of 200mL and 6 (7.5%) after 500mL. Qualitatively, the presence of gastric fluid occurred in more volunteers after fluid ingestion, especially 500mL (18.7%), although not statistically significant.

CONCLUSION

Ultrasound assessment of gastric volume showed no significant difference, both qualitative and quantitative, 2h after ingestion of 200mL or 500mL of isotonic solution compared to fasting, although gastric fluid content has been identified in more volunteers, especially after ingestion of 500mL isotonic solution.

What is the manner of gastric emptying after ingestion of liquids with differences in the volume under uniform glucose-based energy content?

BACKGROUND & AIMS

We previously demonstrated that the gastric emptying rate of liquids chiefly depended on the total amount of calories (energy content) in a uniform volume. The aim of the present study was to examine the effects of different volumes of liquids with a uniform energy content on gastric emptying.

METHODS

Three types of test solutions were prepared with a uniform amount of calories (200 kcal provided by glucose) and step-wise increments in volume (200 ml, 400 ml, and 600 ml). The gastric volume of each solution was determined by ultrasound measurements of the gastric antral cross-sectional area after their ingestion by 8 healthy volunteers.

RESULTS

The mean gastric volume decreased exponentially to nearly 0 ml 70 min after ingestion in the 200 ml group, 90 min in the 400 ml group, and 100 min in the 600 ml group. Each gastric emptying curve converged with identical slopes on the graph when the points at which the gastric emptying curves of the 200 ml and 400 ml groups reached the zero point on the Y-axis (mean gastric volume) were shifted toward 110 min on the X-axis (time scale).

CONCLUSIONS

The volume of liquid ingested with a uniform glucose-based energy content is a critical determinant of liquid gastric emptying. The gastric emptying time may be predicted following the ingestion of an isocaloric liquid with any volume over a predefined range once a gastric emptying curve following the ingestion of a liquid has been plotted on a graph.

TRIAL REGISTRY NUMBER

UMIN000014930.